Interventional Magnetic Resonance Imaging (I-MRI) provides an image-guided, minimally invasive method for ablating cancerous tumors. When a small diameter RF probe is inserted into a solid tumor, the energy delivered by the probe produces a current that heats the tissue to a sufficiently high temperature to kill tumor cells. This project is intended to quantify and predict the acute response of tumor cells and surrounding tissue to heat produced internally with a RF probe. A quantitative model analysis is essential in dealing with special challenges for clinical implementation such as ablating tumor cells near critical vessels or nerves. Furthermore, modeling can assist in predicting changes in the ablated region from the thermal response in tissue with a spatially varying perfusion. To accomplish these goals, we propose to analyze the dynamic changes of the three-dimensional (3-D) temperature field in tissue surrounding the RF heating probe during ablation. This process will be modeled using a 3-D bio-heat equation that incorporates a variable heat source and a distinct temperature-dependent perfusion to represent changes in tissue associated with ablation. The model will be solved numerically to simulate the temperature field dynamics in tissue. We will validate the model and estimate model parameters by comparison of model predictions of the temperature field during RF heating with corresponding data from MRI experiments using gel phantoms, excised tissues, and intact animals. We will develop faster numerical methods for solution of the model equations to allow more accurate, real-time simulations during the ablation procedure. The ablation analysis will include optimal estimates of model parameter estimation, multiple repositioning of the RF probe for sequential tumor ablation, and graphical displays. These methods will assist clinical evaluation and decision-making during the therapeutic procedure to kill tumor cells with minimal damage to normal cells.